Observation of dipolar transport in one-dimensional photonic lattices

TL;DR

This study experimentally investigates how dipolar and fundamental modes propagate in one-dimensional photonic lattices, revealing that dipolar modes spread more due to larger coupling and can traverse disordered systems better than fundamental modes.

Contribution

It provides the first experimental comparison of dipolar and fundamental mode transport in 1D photonic lattices, highlighting the enhanced mobility of dipolar modes.

Findings

Dipolar modes have over twice the coupling constant of fundamental modes.

Dipolar modes can propagate through weakly disordered arrays, unlike fundamental modes.

Dipolar modes exhibit larger spreading areas during propagation.

Abstract

We experimentally study the transport prop- erties of dipolar and fundamental modes on one di- mensional (1D) coupled waveguide arrays. By carefully modulating a wide optical beam, we are able to effec- tively excite dipolar or fundamental modes to study discrete diffraction (single-site excitation) and gaussian beam propagation (multi-site excitation plus a phase gradient). We observe that dipolar modes experience a larger spreading area due to an effective larger coupling constant, which is found to be more than two times larger than the one for fundamental modes. Addition- ally, we study the effect of non-diagonal disorder and find that while fundamental modes are already trapped on a weakly disorder array, dipoles are still able to prop- agate across the system.